"The normal heart rate at rest is usually between 60 and 100 beats per minute."

1.00 to 1.67 Hz

The heart is a muscular organ that is about the size of a closed
fist for an average adult and weighs about 11 ounces (310 grams).
When the heart muscle, called cardiac muscle, contracts it pushes
blood through the chambers and into the vessels. The heartbeat
is a vital, involuntary action for a living human being and the
heart continues to pump throughout an individuals life stopping
only at death. The heartbeat rate is controlled by the autonomic
nervous system, which is composed of two parts -- the sympathetic
system speeds up the heartbeat rate while the parasympathetic
system slows it down.

Heartbeats vary depending on various factors such as age, physical
state, and stimuli. A child has a smaller heart and therefore
their heart needs to beat faster in order to pump the proper amount
of blood. The heartbeat rate for infants is 120 per minute, for
a child is about 90 times per minute, and for a person over age
18 is about 70 times per minute. A physically fit person has a
lower heart rate as compared to an inactive person. Stimuli resulting
in stress, fear or excitement will result in a rapid heartbeat.
Nerves connected to the heart regulate the speed with which the
cardiac muscle contracts. Interestingly, in an average lifetime,
the heart continuously beats more than 2.5 billion times.

People with heart disease produce irregular sounds that are
emitted for each heartbeat. Their blood flows through abnormal
valves causing murmurs -- an important diagnosis for cardiac diseases.
A pacemaker is an electrical device that is used to stimulate
regular beating of the heart for people who have heart disease.

Frequency is denoted as the number of times a regularly recurring
phenomenon occurs in one second. The number of times a heart beats
in one minute is divided by 60 seconds to obtain the frequency
in Hertz. The values for frequency of heartbeat that I researched
were of little variation -- about 70 beats per minute for a healthy
resting adult.